Abstract The goal of this project is to develop a safe and effective targeted MRI contrast agent for accurate early detection and differential diagnosis of high-risk prostate cancer. Prostate cancer is a highly heterogeneous disease and the second most cause of cancer death of men in the US. Early accurate detection and differential diagnosis of high-risk prostate cancer are critical for physicians to tailor efficacious interventions to treat the disease earlier at a treatable stage. We propose to develop a novel molecular imaging approach that targets an oncoprotein associated with epithelial-to-mesenchymal transition (EMT), cancer cell stemness, angiogenesis, proliferation, and metastasis. The oncoprotein has a high expression in the tumor extracellular matrix of high-risk prostate cancer, low in low grade tumor, none in normal tissues. Non-invasive high-resolution MRI of the oncoprotein holds a great promise for accurate localization and differential diagnosis of high-risk prostate cancer. The specific aims of the project are 1) to optimize peptide-targeted MRI contrast agents specific to the oncoprotein in high-risk prostate cancer and to establish mouse prostate PDX models; 2) to perform preclinical evaluation of the targeted MRI contrast agents; 3) to determine the effectiveness of the targeted MRI contrast agents for early detection and differential diagnosis of high-risk prostate cancer in animal tumor models, including patient-derived tumor models, and the toxicity of a lead targeted contrast agent. We have demonstrated the feasibility of our targeted contrast agents in detection and differential prognosis of high-risk prostate cancer in animal models. Multidisciplinary approaches will be applied by a strong research team with complementary expertise in molecular imaging, uro-oncology, pathology, cancer biology, and MRI physics from Case Western Reserve University and Cleveland Clinic in this project. We will identify a lead targeted contrast agent to initiate comprehensive preclinical and clinical development. The targeted contrast agent will have the potential to provide early detection, localization, and differential diagnosis of high-risk prostate cancer. It can also be used for risk stratification, active surveillance, and image-guide therapy of prostate cancer in clinical practice. Success in this endeavor is not limited to better clinical management of the disease, but will also provide exceptional economic and social benefit.